The present invention is generally in the field of valves and in particular, it is concerned with a combined valve for use in vehicle fuel tanks having multi purpose qualities.
A large variety of valves for use with vehicles"" fuel tanks are known. For example, U.S. Pat. No. 5,738,132 discloses a roll over vent valve (ROV) comprising a housing formed with an inlet and an outlet, said outlet comprising a slit-like aperture, and a float member located within the housing axially displaceable between said inlet and said outlet. An elongated flexible closure member strip is anchored at one end thereof adjacent said outlet and a spring biases the float member in direction of said outlet.
The arrangement is such that the spring biasing force together with buoyancy forces acting on the float member tend to press the membrane strip into sealing engagement with the outlet aperture and gravity forces acting on the float member tend to displace the float member away from the outlet so as to progressively detach the strip from sealing engagement with said outlet.
However, displacement of the float member into the sealing position occurs rapidly wherein said outlet aperture is spontaneously sealed as the closure membrane strip rests against a valve seating of said outlet.
In addition, disengagement of the closure membrane strip from the valve seating might be somewhat delayed, in particular under high pressure. Even more so, this valve is not suitable for discharge of fuel vapor at high flow rates.
U.S. Pat. No. 5,762,090 is an over filling interdiction valve (OFI) comprising a housing furnished with a first fluid inlet at a bottom end thereof and a first fluid outlet at a top end thereof, a float axially displaceable within the housing. The float comprises at its bottom end a second fluid inlet and near its top end a second fluid outlet with sealing means associated at a top end of the float member and biasing means are provided within the housing for biasing the float member towards the first outlet.
The arrangement is such that the biasing means together with buoyancy forces acting on the float member tend to urge the float member to a sealing position in which the sealing means sealingly engage with a first fluid outlet, while gravity force acting on the float member tend to displace the float member away from the first fluid outlet to a unsealed position. The valve is characterized in that it further comprises means for restricting fluid ingress into the float member, wherein raising of the fluid level in the tank results in the rise of fluid level within the housing, as a consequence of which the float member is urged to the sealing position. These restricting fluid ingress means reopen once the vehicle starts moving.
It is an object of the present invention to provide a multi functional valve, for use in vehicle fuel tanks which valve simultaneously serves as an over filling interdiction valve (OFI), a vapor recovery valve, a roll over valve (ROV), a filling limit vent valve (FLVV), an onboard refueling vapor recovery valve (ORVR) and as vent valve. It is a further object of the present invention to provide a valve of improved design wherein displacement into its sealing position does not generate a pressure shockwave within the fuel tank on the one hand, and, on the other hand, provides opening of the valve, even under essentially high pressure.
In accordance with the present invention there is provided a valve for use, in particular, with vehicles"" fuel tanks the valve comprising: a housing defining a confined space formed with one or more fluid inlets to said confined space, a fluid outlet port at a top end of said confined space, and a valve seating bounding said outlet port;
a valve assembly located within the confined space and comprising a first stage member and a second stage member, both being substantially coaxially displaceable within the housing;
said first stage member having at a bottom end thereof a substantially elongated slit-like inlet aperture, and at a top end thereof an outlet aperture being in flow communication with said inlet aperture, where said first stage member is axially displaceable between a first position in which the outlet aperture progressively sealingly engages the outlet port of the housing, and a second position in which it is disengaged therefrom;
said second stage member being a float fitted with a flexible closure membrane strip anchored at one end thereof to a top wall of said float member, said closure membrane facing said inlet aperture of the first stage member, the second stage member being displaceable between a first position in which the closure membrane sealingly engages said inlet aperture, and a second position in which it is progressively disengaged therefrom;
at least one anchoring member extending between the first stage member and the second stage member, wherein displacement of the second stage member into its second position entails positive displacement of the first stage member into its second position.
Typically, the outlet port of the valve is connected by suitable piping, to a vapor treating device, e.g. a canister.
The arrangement in accordance with the present invention is such that at an upright position of the valve, buoyancy forces acting on the second stage member tend to displace the second stage member and the first stage member into their respective first positions where the valve is sealingly closed, whilst gravity forces acting on the second stage member tend to displace it into its second position, entailing delayed displacement of the first stage member into its second position; and in a downright position of the valve, the first stage member and the second stage member are instantaneously displaced into their respective first positions so as to seal the valve.
In accordance with a specific embodiment there is further provided a biasing member located within the confined space for biasing the second stage member into its first position acting together with the buoyancy forces so as to displace both the first stage member and the second stage member into their respective first positions.
Typically, where the valve is to be attached to a vehicle""s fuel tank, the housing is formed with a flanged portion for attachment around an opening formed in the tank, with the housing projecting into the tank.
In accordance with the invention, the uppermost inlet of the one or more fluid inlets in the housing, determines the maximum fuel level within the tank, namely when liquid in the tank reaches this level thus, the valve gradually closes entailing fuel filling cut-off.
By a preferred design of the valve in accordance with the invention, the fluid outlet of the housing has a circular cross-section, and the outlet aperture of the first stage member is a tubular projection receivable within said fluid outlet and wherein the first stage member is gradually displaceable into the first position, whereby fluid flow through the fluid outlet diminishes until complete cutoff. Preferably, one or both of the outlet of the housing and the outlet aperture of the first stage member taper upwardly. This arrangement provides gradually diminishing of the effective cross-sectional area of the outlets of the housing whereby a gentle shut-off of the valve occurs.
In order to provide improved sealing in the closed position, a sealing member is provided on either or both of the outlet of the housing and the outlet aperture of the first stage member, whereby sealing engagement occurs only when the first stage member is fully displaced into its first position.
The arrangement in accordance with the invention is such that the length of the one or more anchoring member ensures that when the second stage member is in rest over a bottom base of the housing, the first stage member is in its second position. In accordance with one embodiment, the anchoring member is one or more leg portions extending from one of the first stage member and the second stage member and formed with a hooking portion; said leg portions being slidingly engaged with the other of said first stage member and the second stage member.
For providing improved opening of the valve, also at essentially large pressures, the inlet aperture of the first stage member is inclined with respect to a longitudinal axis of the housing. Correspondingly, a top surface of the second stage member bearing the closure membrane is substantially equally inclined with respect to said longitudinal axis, whereby said closure membrane, when in sealing engagement with said inlet aperture, is pressed along its length against the inlet aperture by said inclined surface of the second stage member.
In accordance with a preferred embodiment of the invention, the first stage member and the second stage member are rotatably restrained with respect to one another. Still preferably, they are rotatably restrained with respect to the housing.